// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
#define MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_

#include <stdint.h>

#include "base/macros.h"
#include "base/memory/shared_memory.h"
#include "base/sync_socket.h"
#include "base/threading/platform_thread.h"
#include "base/threading/thread_checker.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"

namespace media {

// Data transfer between browser and render process uses a combination
// of sync sockets and shared memory. To read from the socket and render
// data, we use a worker thread, a.k.a. the AudioDeviceThread, which reads
// data from the browser via the socket and fills the shared memory from the
// audio thread via the AudioDeviceThread::Callback interface/class.
class MEDIA_EXPORT AudioDeviceThread : public base::PlatformThread::Delegate {
public:
    // This is the callback interface/base class that Audio[Output|Input]Device
    // implements to render input/output data. The callbacks run on the
    // thread owned by AudioDeviceThread.
    class Callback {
    public:
        Callback(const AudioParameters& audio_parameters,
            base::SharedMemoryHandle memory,
            int memory_length,
            int total_segments);

        // One time initialization for the callback object on the audio thread.
        void InitializeOnAudioThread();

        // Derived implementations must call shared_memory_.Map appropriately
        // before Process can be called.
        virtual void MapSharedMemory() = 0;

        // Called whenever we receive notifications about pending input data.
        virtual void Process(uint32_t pending_data) = 0;

    protected:
        virtual ~Callback();

        // Protected so that derived classes can access directly.
        // The variables are 'const' since values are calculated/set in the
        // constructor and must never change.
        const AudioParameters audio_parameters_;

        base::SharedMemory shared_memory_;
        const int memory_length_;
        const int total_segments_;
        const int segment_length_;

        // Detached in constructor and attached in InitializeOnAudioThread() which
        // is called on the audio device thread. Sub-classes can then use it for
        // various thread checking purposes.
        base::ThreadChecker thread_checker_;

    private:
        DISALLOW_COPY_AND_ASSIGN(Callback);
    };

    // Creates and automatically starts the audio thread.
    AudioDeviceThread(Callback* callback,
        base::SyncSocket::Handle socket,
        const char* thread_name);

    // This tells the audio thread to stop and clean up the data; this is a
    // synchronous process and the thread will stop before the method returns.
    ~AudioDeviceThread() override;

private:
    void ThreadMain() final;

    Callback* const callback_;
    const char* thread_name_;
    base::CancelableSyncSocket socket_;
    base::PlatformThreadHandle thread_handle_;

    DISALLOW_COPY_AND_ASSIGN(AudioDeviceThread);
};

} // namespace media.

#endif // MEDIA_AUDIO_AUDIO_DEVICE_THREAD_H_
